I bought a water pump for my '80 900GL as many of you may already know, but I
decided to get new seals anyway and rebuild my own pump. I decided
to dissassemble the pump I bought just for practice. I followed
instructions at first, supporting the impeller and tapping the shaft with a
drift. It wouldn't budge at all. So I got a gear puller from a
buddy and started cranking on it with a ratchet and all of a sudden
SNAP! The impeller busted! Not a terrible loss because the shaft
gears on the pump I bought were busted anyway, but I am thinking if
that happened what is to say I'll be able to remove my own impeller?
I looked more carefully at the impeller and shaft that broke and it
appears they are welded together?!? Was that the case with some of
them? All I know is if I can't do a better job dissassembling my
own pump I am @#$&ed......

Edit:

I have pounded on the head of the shaft with a hammer with all the force I can muster. To the point where the shaft snapped in half and till the top of the shft is mushroomed and it hasn't budged a millimeter. I KNOW for a fact it's welded on. The question is, why? and who did it? and is there any chance my own pump is welded together?

Well I got a good suggestion.....One guy told me to take it to a machinist and get them to press it off. So as much as it pains me to do it it seems to be the most sensible idea yet.....I just hope it doesn't cost that much....

I thought you said that the pump had only a few hundred kms on it? Did it have knackered teeth when you go it?

There's no way the impellor should have been welded on! They are a slight interference fit, but need to be dismantled to service and reinstall them. Have you pulled the pump from your car yet? What sort of condition is that in? If it's ok, then use the seals you've bought and refurbish that one. Remember to get the impellor sealing face cleaned up though.

Since you say "the shaft gears on the pump you bought were bad anyway". I am assuming you bought a used pump from a junkyard or something like that.

One thing I have found is that although parts from different years will work between different years of the same model, many times the parts are different.

I can list example anter example, but it won't help you fix your water pump.

Secondly, If you did get a used pump off a junk car, how do you know if the pump is OEM? Possibly the pump is a cheap "autozone" type aftermarket replacement pump.

I can't give you any advice about the pump rebuild, since I have not rebuilt any.

I commend you for trying to rebuild a faulty part, in a world that is insistant on component replacement when things fail... Hopefully you will be able to rebuild the original pump.

Jay

Jay, the earliest 900 and all but the last 99's have a water pump like no other They are a pile of bits that you assemble and press into the block in a certain order then screw a cover over them. When treated well they can last for a long time, but if neglected can be a right nightmare!

Touch wood I've been fortunate with mine, but I am prepared for the worst